Such computer keyboards are widespread as independent peripheral devices or as integrated input system in case of portable computers, especially notebooks.
Especially for working with graphic user interfaces and using a menu navigation typically implemented here, it is usual to provide, besides a keyboard, also a pointing device like e.g. a computer mouse, a track ball, a graphic tablet or—especially for notebooks—a touch pad. By means of this pointing equipment in a well-known way cursor positions can be manually coordinated. The movements of a cursor correlate with a movement of the mouse, or a movement of a finger on the touch pad.
Pointing equipment typically also includes additional keys or input elements with which determined operations can be carried out, e.g. a left, middle, and right mouse button for selecting elements of the user interface, a scroll wheel, a wheel button and/or additional keys alongside the mouse or a strip on a touch pad, in which a contact and movement of the finger entails a scrolling, as well as special functions provided in the corners of a touch pad. The functions of some or all these additional keys or input elements can be also configured by the user, e.g. special function calls of the operating system if pressing an additional mouse button or if touching a certain corner of the touch pad.